Unexpected Positive Cultures After Failed Proximal Humerus Osteosynthesis: Why a Two-Stage Procedure Could Be Safer

Background: Treatment of failed osteosynthesis of fractures of the proximal humerus with one-stage or two-stage surgery is difficult and clinical results are poor. The aim of this work is to evaluate the microbiological positivity of devices removed due to osteosynthesis failure. Furthermore, the clinical outcomes of these patients were evaluated at a follow-up of minimum 6 months, to assess the recovery of range of motion and the reduction in pain. Methods: A retrospective analysis was performed on 15 patients treated from September 2021 to September 2023 for failure of previous proximal humerus synthesis. These treatments included implant removal and arthrolysis. None of these patients showed signs of infection. Demographic data, VAS, ASES, Constant score, and range of motion (ROM) were assessed before surgery and at least 6 months of follow-up. Removed devices were processed in MicroDTTect^® system, to increase the sensitivity of microbiological cultures. The cultural and clinical results of device removal surgery were analyzed. Results: Culture results were positive in eight out of 15 patients. Slow-growing anaerobic bacteria were the most isolated microorganisms, particularly C. acnes (62.5%). Improvement in patients' passive ROM was observed. The patients went from a preoperative VAS of 8.4 (±1.1) to a VAS of 2 (±1.1) at follow-up. Similarly, we observed an increase in ASES from 9 ± 6 to 50.2 ± 2.3 and Constant score from 17 (15-18) to 40.7 ± 3.3 at a follow-up of at least 6 months. Conclusions: Two-stage procedure should always be considered in the context of proximal humerus synthesis failure. Arthrolysis with postoperative physiotherapy prepares the shoulder for definitive prosthesis implantation.